Pressure sensitive record material



Patented pr. 25, 195% National Cash Register Company, Dayton,

Ohio, a corporation of Maryland No Drawing. Original application November 8,

1947, Serial No. 784,938. Divided and this application November 10, 1948, SerialNafiQAZS (Cl. Ill-36) 12 Glaims. i

This invention. relates to improvements in pressure-sensitive, record material. This appli cation is a divisionoithe pending application of Barrett K. Green, Serial No. 784,938, filed Novemher 8, 1947, for pressure-sensitive record material.

The principal object oi this invention is to provide a pressure-sensitive record material on which a mark of distinctive color may be produced by the mere application of localized pressure and which is not subject to the disadvantages inherent in the pressure-sensitive record material disclosed in United States Letters Patent No. 2,299,693, patented October 20, 1M2, on the application by Barrett K. Green onFehruary 23, 1M0. That patent discloses apressure-sensitive record material including the combination of an insulatin medium, a rupturable solid material such as gum dammar, having included therein interspersed droplets of a plurality of liquid reagents, which are chemically reactive to produce a distinctive color in the record material at the points crapplication of localized pressure thereto, such pressure rupturing the. insulating medium to permit chemical reactionbetween the two liquidreagents. The two reagents disclosed. in this patent are gallic acid and ferric ammonium sulphate, each dissolved in glycerine. These reagents are ionized. by the glycerine, which. constitutes. an ionizing medium, and the chemical reaction proceeds by interchange of ions when the two solutions are allowed to mix, upon the rupture of the insulating medium. The reaction disclosed in that patent depends upon the presence of the reagents inan ionizing medium. However, any available ionizing medium is hygroscopic, with the result that the record material made inaccordance with this patent is sensitive to an excess of moisture, and con ditions of high humidity may cause theinsulating medium to cease to be efiective, with. the result that the chemical reaction takes place without any application of localized pressure, and the: record material is stained and discolored; so that it ceases to be useful As stated aboverthe principal object of the present invention is'to provide a pressure-sensi tiverecord material that is not subject to the defects and disadvantages of that disclosed in Patent No. 2,299,693,- asindicated above.

Another obiectof'the-present invention is to provide a recordmaterial upon which a mark of distinctive color maybe produced, at the points of; application of localized pressure thereto, by such mere application cfl'ocalize'd pressure, and which will not become discolored or stained" due to In short, it the objectof-this. invention to provide a pressure-sensitiverecord material in which the mark of. distinctive color. will be produced only at the pointsoi application OfIOCEJQ ized pressure, and at no-other points; and under. no other conditions.

Another object of this invention is to: provide a pressure-sensitive. record material in which the mark of distinctive color is producedby the chemical reaction of color-forming reactants, in the absence of any liquidionizing medium therefor.

A further object of this invention is to provide a pressure-sensitiverecord material in. whicha",

is clearly defined and pointedouti in theappendedx claims.

In general, the present invention contemplates a pressure-sensitive record material comprising,

in combination, aplurality of adsorption color forming reactants, such reactants being so selected that they react, in the absencecfsa liquid. ionizing medium for thereactants, to form a distinctive color when brought into adsorption con tact with each other, and. a solid: insulating me-- dium insulating saidzreactantsfrom color-form ing reaction contact with each other. Upon applicaticn of localized pressureto the record material, as by drawing a stylus across. it, the. insulating medium is ruptured at, the points ofapplication of said localized pressure, and such rupture permits color-forming reaction contact between the reactants at such points, in the absence of any liquid ionizing medium for said reing.

actants. The result is that. a mark of distinctive color is produced by the mere application of localized pressure.

The cclor-formingreactlon employed is of the, sc-called, adsorptiorrtype in which an inorganic compound causes a color change in any organic cor pound upon adsorption: contact therewith.

0f the reactant materials employed the organic material is an electron; donor aromatic compcund having a double bond. system which. is

convertible to a more highly polarized conjuform upon taking, part in an electron. accenters-donor solid. surface.chemicalreaction, giving it adistinctive. colonandthe inorganicmate'rial is a material which actsas. an acid. rela asoasve tive to the organic material so as to be an electron acceptor when in adsorption contact therewith. Both materials are in fine particle form in order to furnish a large reactant surface area per unit area of the record material which enhances the depth of color per unit area of the record ma terial.

In the preferred form of this invention, both of the color-forming reactants, as well as the insulating medium, are in the solid state, and the color-forming reaction takes place upon mere contact of solid particles of the reactants. A pressure-sensitive record material may be provided in which the solid particles of a plurality of color-forming reactants are dispersed in a solid insulating medium, which insulates the particles from color-forming reaction contact with each other. The rupture of this solid insulating medium by the application of localized pressure permits the solid particles of color-forming reactants to react with each other, at the points of application of such pressure, to produce the mark of distinctive color. According to one form of this invention, solid particles of one of the color-forming reactants are carried by and dispersed in a solid insulating medium, to which a coating of solid particles of another color-forming reactant is applied. In this case, the application of localized pressure ruptures the solid insulating medium at the points of application of such pressure and brings about color-forming reaction contact between the solid particles of color-forming reactants at such points, thus producing the mark of distinctive color. Preferably, this pressure-sensitive record material includes a base web, such as a fibrous web of paper or the like, to which the coating of solid insulating medium and the color-forming reactants is applied.

Since it is difiicult to show precisely the spatial relat onship between the solid particles of colorforming reactants, the solid insulating medium, and the base web, it is preferred not to attempt to illustrate any embodiment of this invention by drawings.

In the following examples, there will be described embodiments of this invention, by means of which the objects of the invention have been successfully attained.

A pressure-sensitive record material constituting an embodiment of this invention consists of a web of paper having applied thereto a coating including casein as the solid insulating medium and solid particles of two color-forming reactants, kaolin and the compound 3,3 bis(4-dimethyl amino Si-methyl phenyl) phthalide, having the structural formula This record material is normally white, but a blue mark is produced thereon by the application of localized pressure, which ruptures the insulating medium, casein, and permits color-forming reaction contact between the solid particles of the reactants at the points of application of such localized pressure.

The compound 3,3 bis(4-dimethylamlno 3 methyl phenyl) phthalide, referred to above, is described and claimed in United States Letters Patent of Clyde S. Adams, No. 2,443,092.

This record material has been made successfully by first coating a web of paper with a solution of casein having solid particles of kaolin dispersed therein, the ratio of kaolin to casein being about ten to one. The coated paper was then dried, and there was applied to the coated side of the paper a 3% by weight solution in toluene of 3,3 bisOi-dimethylamino 3 methyl phenyl) phthalide. The excess of solution was removed from the paper, and the treated paper was dried to evaporate the solvent, leaving a deposit of solid particles of the compound in and upon the film of casein, in which the solid particles of kaolin are dispersed.

When these ingredients are applied to the paper as a coating thereon, such coating should weigh about .0023 pound per square foot of surface and may have a thickness of the order of from .0905 to .001 inch. The thickness of the coating varies, of course, with the treatment to which the record material is subjected in finishing. The solid particles of kaolin in this record material may be of about the order of ten microns in diameter, although considerable variation in particle size is possible Without any ill eifects. Particle size of the phthalide compound is largely determined by the method of application of that ingredient. The particles of these reactants may be as large as ten microns in diameter and frequently are much smaller.

Organic hydrophilic colloid substances such as gelatin, methyl cellulose, starch, polyvinyl alcohol, and animal glue are representative materials that may be substituted for casein as the solid insulating medium. Any of the following inorganic materials may be substituted for kaolin as one of the color-forming reactants: attapulgite (Attapulgus clay), pyrophyllite, talc, bentonite, halloysite, calcium sulphate, calcium citrate, magnesium trisilicate, zinc sulphide, zirconium dioxide, calcium phosphate, barium sulphate, and calcium fluoride. When any of these materials are substituted for the kaolin in this combination, the resulting record material will be white or bluish white in color, and a blue mark will appear thereon as the result of the applica tion of localized pressure.

One method that has been used successfully to make the pressure-sensitive record material described above is as follows: A slurry of kaolin and water was prepared including fifty parts by weight of kaolin to fifty parts by weight of water, and a small amount of a suitable dispersing agent, such as sodium metaphosphate, for instance, in the proportion of 0.075% by weight was added to facilitate the dispersion of the particles of kaolin throughout the slurry. The addition of this dispersing agent reduces the viscosity of the slurry considerably, thus facilitating its mixing and application and also preventing the settling of the solid particles of kaolin. A 20% by weight solution of casein in water was formed by, first,

dispersing the casein in cold water by stirring for fifteen minutes at room temperature and, then, heating up to degrees centigrade. Five parts by weight of a 28% ammonium hydroxide solution-that is, one having a specific gravity of 25.9 B., at

presence weretheniadded to thel hot:caseimsolutiomwntch wasstirred'ionabout fifteen;minutesiandiallowed to cool to room temperature. "The hao'l'in 'slurry and the alkaline casein :solution were then thoroughly-mixed and blendedain the ratioactiten parts by weight or kaolin to one part 'ofzcasein,

and, at' this stage, a"small percentage for instance, about 0.05% by weight-of tributyl phos phate in alcohol,m or otheranti-foaming agent,

was added. This mixture .of the kaolin slurry dried torevaporate the .toluene and wasxreadyiifor use.

The methods "and processes 'of making 'pressure-sensitive record material disclosed herein are not claimed in thiseapplication :but "are :dis-

closed and cla med in the pending appiication of Barrett K. Green, Serial No. 784,939, filedNovemher 8. 1947, for the Process for making pressuresens'itive record imaiterial, and inthe division thereof, SerialNo. 63,2l8,fiIedDecember flg 1948 It is understood that the pressure-sensitive record material described herein is susceptible of considerable var ation without'departing from the spirit of the invention.

What is claimed is:

l. Pressure-sensitivereeord material including the combinat on of a supporting member, a plurality of adsorption color-forming reactants in the solid state, so-selected as to react in the absence of a liquid ionizing medium for the reactants to form a distinctive color when brought into contact with each other, at least one of said reactants being an inorganic compound and at least another one of said reactants being an organic compound, disposed in proximity to each other, and a solid insulating medium, derived from an organic film-forming hydrophilic colloid material, insulating said reactants from color-forming reaction contact with each other, the application of localized pressure to the record material rupturing said insulating medium at the points of application of such pressure to permit color-forming reaction contact between the reactants at such points, whereby a mark of distinctive color is produced by mere application of localized pressure, one of said color-forming reactants being the organic compound 3,3 bis(4- dimethylamino 3-methyl phenyl) phthalide, having the structure and the inorganic reactant being in fine particle form providing a large adsorbent surface area and which is an acid relative to the organic reactant so as tobe an electron acceptor when in adsorption contact with the organic reactant, the

said; :reactants' dieing; iadsorbable. .onie upon the other;

2. The record material ofclaim l in which the inorganic color-forming reactant is kaolin.

3. The record material of claim .2 in which the solid insulating medium is casein.

4. Pressure-sensitive record material including the combination of a supporting member, solid particles of a plurality of adsorption colorforming reactants disposed in contiguity to each other, and a solid insulating medium, derived from an organic film-forming hydrophilic colloid material, insulating said solid reactant particles from color-forming reaction contact with each other, at least one of the reactants being andnorganic compound and :at least anotherione of'the "reactantsbeing an organic compound adsorbable one 'upon'the other, said reactants "being soslectedas to .react to form a distinctive color when particles of each are brought into adsorption contact, the application of localized pressure to the record'material rupturing saidinsulatingmedium at the points of application of such pressure to 'permit color-forming reaction contact of the solid reactant particles at such points, whereby'a mark of distinctive color isproduced'by mere application of localized pressure, one of the color-forming reactants being the organic compound 33 bista-dimethylamino 3- methyl phenyl) "phthalide, having the structure and the inorganic reactant being in fine particle form to provide a large adsorption surface area 7 and which is an acid relative to the organic compound so as to act as an electron acceptor when in adsorption contact with the organic compound.

5. The record material of claim 4 in. which the inorganic color-forming reactant is kaolin.

6. The record material of claim 5 in which the solid insulating medium is casein.

'7. Pressure-sensitive record material including the combination of a supporting member, a solid insulating medium derived from an organic filmforming hydrophilic colloid material, solid particles of a first color-forming reactant dispersed therein and solid particles of a second color-forming reactant deposited thereon, said solid insulating medium insulating said solid reactant particles from color-forming reaction contact with each other, one of said reactants being an inorganic compound and the other of said reactants being an organic compound one adsorbable upon the other, said reactants being so selected as to react, in the solid state, to form a distinctive color when brought into adsorption contact with each other, the application of localized pressure to the record material rupturing said insulating medium at the points of application of such pressure to permit color-forming reaction contact of the solid reactant particles at such points, whereby a mark of distinctive color is produced by mere application of localized pressure, the second color-forming reactant being the organic compound 3,3 bis(4-dimethylamino 3- methyl phenyl) phthalide, having the structure (CH3)aN N(CHs):

and the inorganic reactant being in fine particle form to provide a large adsorption surface area and which is an acid relative to the organic compound so as to act as an electron acceptor when in adsorption contact with the organic compound.

3. The record material of claim 7 in which the first color-for1ning reactant is kaolin.

9. The record material of claim 8 in which the solid insulating medium is casein.

10. Pressure-sensitive record material including the combination of a base web and a coat? ing thereon, said coating including a plurality of adsorption color-forming reactants in the solid state, so selected as to react in the absence of an ionizing medium to form a distinctive color when brought into contact with each other, at least one of said reactants being an inorganic compound and at least another of said reactants being an organic compound adsorbable therewith, and disposed in p oximity to each other, and a solid insulating medium, derived from an organic film-forming hydrophilic colloid substance, insulating said reactants from color forming reaction contact with each other, the application of localized pressure to the record material rupturing said insulating medium at the points of application of such pressure to permit color-forming reaction contact between the reactants at such points, whereby a mark of distinctive color is produced by mere application of localized pressure, one of the color-forming reactants being the organic compound 3,3 bis(4-dimethylamino 3-methyl phenyl) phthalide, having the structure I CH3 CH3 (CHa):N- N(CH3):

REFERENCES CITED The following references are of record in the file of this patent:

FOREIGN PATENTS Number Country Date 550,332 Great Britain Jan. 4, 1943 

1. PRESSURE-SENSITIVE RECORD MATERIAL INCLUDING THE COMBINATION OF A SUPPORTING MEMBER, A PLURALITY OF ADSORPTION COLOR-FORMING REACTANTS IN THE SOLID STATE, SO SELECTED AS TO REACT IN THE ABSENCE OF A LIQUID IONIZING MEDIUM FOR THE REACTANTS TO FORM A DISTINCTIVE COLOR BROUGHT INTO CONTACT WITH EACH OTHER, AT LEAST ONE OF SAID REACTANTS BEING AN INORGANIC COMPOUND AND AT LEAST ANOTHER ONE OF SAID REACTANTS BEING AN ORGANIC COMPOUND, DISPOSED IN PROXIMITY TO EACH OTHER, AND A SOLID INSULTING MEDIUM, DERIVED FROM AN ORGANIC FILM-FORMING HYDROPHILIC COLLOID MATERIAL, INSULATING SAID REACTANTS FROM COLOR-FORMING REACTION CONTACT WITH EACH OTHER, THE APPLICATION OF LOCALIZED PRESSURE TO THE RECORD MATERIAL RUPTURING SAID INSULATING MEDIUM AT THE POINTS OF APPLICATION OF SUCH PRESSURE TO PERMIT COLOR-FORMING REACTION CONTACT BETWEEN THE REACTANTS AT SUCH POINTS, WHEREBY A MARK OF DISTINCTIVE COLOR IS PRODUCED BY MERE APPLICATION OF LOCALIZED PRESSURE, ONE OF SAID COLOR-FORMING REACTANTS BEING THE ORGANIC COMPOUND 3,3 BIS(4DIMETHYLAMINO 3-METHYL PHENYL) PHTHALIDE, HAVING THE STRUCTURE 